1. Field of the Invention
The present invention relates to an optical pickup and an optical disk apparatus incorporating the same, and more specifically, to a heat dissipating structure of a laser diode used for the optical pickup.
2. Description of the Prior Art
An optical pickup is used for recording and reading optical disks such as CD (Compact Disk) and DVD (Digital Versatile Disk). FIG. 5 is an exploded perspective view of a conventional optical pickup. An optical pickup 100 has a base 101, an LD (Laser Diode) 102, an LD holder 103, an LD plate 104, a collimator lens 105, a half mirror 106, an upward-directed mirror 107, an FPC (Flexible Printed Circuit) 108, and a PDIC (Photo Detector IC) 109.
FIG. 6A is a cross sectional view showing an essential portion of FIG. 5. FIG. 6B is a bottom view of FIG. 6A. The LD 102 is fitted to the LD holder 103, and the LD holder 103, the LD plate 104, and the base 101 are fixed together. Although they are fixed with screws as shown in FIG. 5, it is also possible to fix them together with an adhesive or the like. In this example, the LD holder is produced through metal forming such as zinc die casting, and the base 101 is made of resin such as PPS. The LD holder 103 is made of metal so as to improve heat dissipation. Furthermore, the base 101 is made of resin, because it has a complicated shape and the resin is inexpensive and easy to process.
Japanese Patent Application Laid-Open No. 2003-187479 also discloses an optical head apparatus that employs a device holder such as the aforementioned LD holder.
Japanese Patent Application Laid-Open No. 2003-272208 discloses an optical pickup having a heat conductive resin interposed between a semiconductor laser and a contiguous portion adjacent thereto. Here, the heat conductive resin is used to fill a gap therebetween and facilitate heat dissipation.
According to the structure shown in FIG. 5 and the structure disclosed in Japanese Patent Application Laid-Open No. 2003-187479, since an LD holder (a device holder in Japanese Patent Application Laid-Open No. 2003-187479) is used, it helps dissipate heat. This, however, leads to an increased component cost. On the other hand, if the LD, without the LD holder, is directly fitted to the base for the purpose of decreasing the cost, the heat dissipation suffers, and this will result in harming the performance of the LD.
As disclosed in Japanese Patent Application Laid-Open No. 2003-187479, if a heat conductive resin is used, it is less expensive but offers poor performance in heat dissipation than the LD holder.